FR2463373A1 - AIR DRYING APPARATUS - Google Patents

Abstract

AIR DRYING UNIT. APPARATUS 10 FOR DRYING A SLURRY WHICH IS TRANSPORTED ON A MOBILE SUPPORT 12 AND WHICH INCLUDES A VAPOR PRODUCTION DEVICE 14 BELOW THE MOBILE SUPPORT TO FORM A VAPOR ATMOSPHERE. A FILM OF CONDENSED STEAM IS PRODUCED BELOW THE SLURRY DUE TO HEAT TRANSFER THROUGH THE MOBILE BRACKET, AND AN AIR DRYER 16 PROPULATES A CURRENT OF AIR THROUGH THE SLOT SURFACE TO TRAIN THE STEAM THAT IT CONTAINS AND ELIMINATE IT FROM THE BOIL. APPLICATION: DRYING RECONSTITUTED TOBACCO Porridge.

Description

The present invention relates to an air drying apparatus.

  and, more particularly, an apparatus for eliminating human

  mordance of an aqueous slurry. Specifically, the invention

  a drying apparatus of a reconstituted tobacco slurry in a relatively fast and uniform manner. Methods and apparatus for drying aqueous slurry such as reconstituted tobacco slurry

  used air hoods, bedrooms and bathrooms.

  costly and cumbersome layouts arranged above and

  around a forming strip of a tobacco leaf. The appeals

  drying machines distribute, collect and transport

  the air necessary for the removal of water vapor from the

  face of the porridge. So far, these hoods, chambers and

  pipelines were necessary to ensure

  extremely uniform drying rate in order to obtain high quality reconstituted tobacco products, such as

  and sub-capes of cigars. It has often been found that these

  ceded and these devices were of such a complex construction

  they did not help reduce costs.

  Among the devices of this type, there is one in which the heating agent, constituted for example by steam, is distributed under an endless belt which carries a

  aqueous slurry so that the water evaporates from the slurry.

  A stream of air is passed through the porridge and this

  air flow causes the evaporated water of the porridge and the

  cue of the device. This apparatus of the prior art

  discontinues the use of fume hoods and complicated

  cumbersome, making it difficult to monitor the regular

the drying of the porridge.

  Various types of air heating and drying apparatus are also known in which the heat and / or the air jet is applied to an aqueous slurry or to a strip of material so as to evaporate and remove the same. humidity. Among the publications of this prior art are U.S. Patent Nos. 3,228,113 to Fannon, Jr., 1,373,396 to Andrews, 3,417,484 to McCarthy and 3,590,493 to Gretz. None of these prior patents discloses a method and apparatus that are completely satisfactory and allow the moisture contained in an aqueous slurry to be rapidly and uniformly removed to the degree necessary when it is a slurry of water.

2. 2463373

reconstituted tobacco.

  There is also known an air dryer in the-

  which a reconstituted tobacco porridge is transported on a

  porous belt that allows the moisture contained in the

  to filter through the belt. This results in an inadmissible loss of nicotine contained in the slurry, which

  requires the separation of nicotine from moisture that has been ex-

  treats, and the replacement of nicotine in dried tobacco.

  With regard to the drying of slurry, and in particular

  the drying of reconstituted tobacco slurries, it is important to

  to obtain a high quality tobacco, the drying of the slurry is carried out rapidly and uniformly

  means of an apparatus allowing to obtain the desired results.

  and impossible to obtain so far according to the prior art,

  while being sufficiently profitable and economical to be

petitive.

  Accordingly, an object of the invention is to create an

  like drying a porridge that is simple and reliable.

  A more specific object of the invention is to create an

  air dryer using air currents to eliminate

  remove evaporated moisture from a slurry, such as a slurry

  of reconstituted tobacco, quickly and uniformly.

  Another object of the invention is to create an apparatus for

  air-drying apparatus of the type described, in which a steam-producing device is disposed below an endlessly moving conveyor belt and supporting the slurry so as to

  produce an atmosphere charged with steam below the

  which causes the evaporation of the moisture contained in the slurry, and in which air nozzles project a current

  of drying air through the slurry to eliminate the

  afraid of water present above the porridge.

  Yet another object of the invention is to create an air drying apparatus for a slurry of the type described, providing a

  uniform and rapid drying of the slurry, and in which the application

  it is simple and inexpensive to construct, requiring only a minimum of piping, maintenance and control, and being therefore very economical and likely to reduce costs both from the point of view of capital investment

than running costs.

  Preferred embodiments of a drying apparatus 3.

--2463373

  constructed according to the invention, given merely by way of example

  ples, will now be described with reference to the accompanying drawings, in which FIG. 1 is a general and schematic perspective view of an air drying apparatus according to the invention, FIG. 2 is a plan view from above of a steam box used in the apparatus of the invention,

  Fig. 3 is a side elevational view of the gearbox

  afraid of fig. 2, FIG. 4 is a sectional view on a larger scale along the line 4-4 of FIG. 2, FIG. 5 is a fragmentary view on a larger scale of the encircled portion of FIG. 2

  Fig. 6a to 6c are side elevational views of the

  air dryer, Fig. 7 is a sectional view on a larger scale along the line 7-7 of FIG. 6a, Fig. 8a to 8c are plan views from above of the apparatus of FIGS. 6a to 6c, FIG. 9 is a front elevational view of a positive ventilation chamber which sends the air used in the apparatus of the invention,

  Fig. 10 is a plan view over the chamber of

  Positive tilation which feeds the air, Fig. 11 is a sectional view along the line 11-11 of FIG. 9, FIG. 12 is a front elevational view of a positive return air ventilation chamber used in the apparatus of the invention,

  Fig. 13 is a plan view over the ventilation chamber

  positive air return air flow, Fig. 14 is a sectional view along line 14-14 of FIG. 12, FIG. 15 is a schematic representation of the apparatus of FIG. 1

  Fig. 16 is a perspective view of another embodiment of the invention.

  the air drying apparatus, FIG. Fig. 17 is a schematic cross-section of another embodiment of the air drying apparatus; 18 is a plan view from above, on a reduced scale, of the apparatus of FIG. 17, FIG. 19 is a schematic perspective view of another embodiment of the apparatus of the invention, FIG. 20 is a schematic cross sectional view of another embodiment of the apparatus of the invention, and FIG. 21 is a plan view from above, on a reduced scale,

of the apparatus of FIG. 20.

  Referring now in detail to the drawings, and in particular to FIG. 1, the slurry dryer 10 of

  the invention comprises a waterproof stainless steel belt 12

  and moving endlessly, the upper horizontal flat strand of this belt carrying a slurry in the form of a thin layer. The slurry may be constituted for example by a tobacco leaf formed from fine particle reduced tobacco as described in US Patent Application No. 18,814 to Schmidt et al. filed March 8, 1979 and referred to herein for reference. The upper strand of the belt 12 moves towards the arrow S at a distance of

predetermined speed.

  Below the upper strand of the belt 12 is arranged

  at least one steam box 14 described in more detail with reference

  in fig. 2, 3, 4 and 5 of the drawings. The steam box ejects steam against the lower surface of the upper end of the endless belt 12 so as to form a vapor-laden atmosphere in the space between the steam box 14 and the lower surface of the upper strand of the belt, and thereby produces a continuous film of vapor condensing over the endless belt 12 and rising from the supported slurry

on the belt.

  At least one air-drying device 16 is arranged along the two longitudinal edges of the endless conveyor belt 12 and at substantially the same axial distance as the

  the steam box 14 along the belt 12. The device for

  air duct 16 consists of at least one ventilation chamber

  positive air outlet 18 which produces an air flow of

  load passing through the upper surface of the courtyard.

  endless conveyor belt 12, in close parallelism with it and towards the inlet of a positive return air ventilation chamber 20 located on the opposite side of the belt 12 and generally in the same plane. As can be deduced from 5.

  the following detailed description of the drying apparatus of

  10, a series of air drying devices 16 are provided along the path of the endless conveyor belt 12 so as to constitute an elongated drying zone, a steam box 14 being located below each device

of air drying 16 respectively.

  Reference being made more particularly to FIGS. 2 to 5

  drawings, each steam box 14 comprises a pair of chambers

  22 and 24 of positive ventilation, elongated, spaced and

  rallies, extending along the path of the trans-

  endless carrier 12 below its opposite edges. A food

  appropriate steam supply is planned to be sent to

  each steam box 14 by input connections 26 from.

  a source of steam (not shown) leading to the chamber

  Positive ventilation chamber 24. Ventilation chambers 22

  and 24 are connected in the form of a rigid structure by

  appropriate verses 28 so as to constitute a box-shaped structure. Positive vent chambers 22 and 24 communicate through a series of parallel, spaced, parallel, tubular conduits 30, preferably of tubular and hollow construction, each having a large number of orifices.

  32 directed upwardly and radially

  latively weak, spaced along its length. As can be seen more clearly from Fig. 4, the positive ventilation chambers 22 and 24 are also connected at the level of each of the tubular conduits 32 by means of tie rods 34

  passing inside and arranged coaxially with conduits 32.

  With regard to the construction of the whole connection

  steam lines 30 with the ventilation chambers po-

  sitive 22 and 24, the series of conduits 30 which are spaced on

  the length of each steam box 14 communicates alternatively

  at each end with one or the other of the positive ventilation chambers 22 or 24, as shown in FIG. 4, and as a result, when the steam passes through the lines 30 from one end to the other, it passes from the positive ventilation chamber 22 to a steam line 30, whereas the

  The following vapor 30 contains steam which comes from the chamber.

Positive ventilation status 24.

  To obtain a tight connection between the steam box 14

  and the lower surface of the upper run of the conveyor belt

  6. endless carrier 32 and thus avoid the escape of steam into

  the environment, a sealing bar 36 extends over the length

  of each positive ventilation member 22 and 24, this

  bar being preferably made of rubber or a

  sealed synthetic material, and its upper surface 38 is in sliding and sealing contact with the lower surface of the upper strand of the endless conveyor belt 12 which is located in an area adjacent to the rim of the latter. In addition, the longitudinally opposite ends of the steam box 14 which are located transversely to the belt 12

  are each provided with a similar sealing member

  placed transversely and is in the form of a scraper to sweep the moisture condensing on the bottom surface of the endless belt 12 and send it into the box.

steam 14.

  A series of freely rotatable rollers 42 are mounted on the shafts 44 extending between the positive ventilation chambers 22 and 24, the upper portion of the circumferential surfaces.

  rollers 42 being substantially in the same plane as the

  upper face 38 of the sealing bars 36 to determine a generally horizontal support device for the upper end of the endless conveyor belt 12, when the belt on which the slurry is placed passes over each steam box 14. A tank condensate trap 46 which connects the positive vent chambers 22 and 24 to the

  level of their funds and which extends over the width that

  which is defined by the length of the pipes 30 determines a closed box-shaped set centrally inclined towards

  the trough-shaped bottom towards a junction with a

  condensate outlet nexion 48 at its lowest point

  to facilitate the exit of water from condensed steam

in the steam box 14.

  With particular reference to FIG. 5, a provision

  Support bracket 50 which is mounted at each end at the corners of the steam box 14 includes an end console 52 to which is attached a vertically mounted eye bolt 54. This allows the steam box to be suspended from an overhanging structure 56 shown in FIG. 7. Structure 56 consists of amounts

  vertically 58 connected at their upper ends by a

  horizontal pour 60, and attached to their lower ends to

7. 2463373

  horizontal supports 62 of the drying apparatus 10 of

  to form a rigid chassis. Eye bolts 64 are

  suspended to the cross member 6a and support cables 66 to

  the entire steam box is suspended below the upper run of the belt 12 by means of the eyebolts

  54 hooked to the lower ends of the cables. This results in

  As movements or lateral movements of the endless conveyor belt 12 passing over the rollers 42 and supporting the upper strand of the belt, and whose lower strand of the belt is supported on rollers 68 mounted on shafts 70 supported by their side on lower supports 62, are not

  not thrown to the steamer 14.

  Referring now to the drying air device

  16 illustrated in FIGS. 6a to 6c and 8a to 8c, this device

  in a series of drying air sections 16 arranged in

  along the length of the upper end of the endless conveyor belt 12 to form a drying zone elongated by the slurry. Each drying air section 16 comprises a positive ventilation chamber 18 which provides air and which extends on one side of the belt 12 and a positive return air ventilation chamber located on the opposite side of the belt, on the same length and aligned longitudinally with the air supply positive ventilation chamber 18, subsequent sections 16 being arranged so that each chamber of

  positive ventilation 18 of air supply comprises a chamber

  positive air return ventilation device disposed downstream

  on the same side of the belt 12.

  Each positive air supply ventilation chamber 18 comprises a blower 72 driven by a motor 74 associated therewith to send it preferably heated air.

and dehunidified.

  As can easily be seen from Figs. 9 to 11, each positive air supply ventilation chamber 18

  essentially consists of a sheet and includes a chamber

  vertical and extended 76 positive ventilation manifold comprising

  closing side walls 78 and 80, the latter is

  curvature at its upper portion to extend as an upper and horizontal closure plate 82, while the

  closure wall 78 is extended into a horizontal wall 84.

  End walls 86 and 88 form with the other walls of the 8.

  virtually closed structures constituting a room for

  positive configuration and whose configuration, as re-

  shown in fig. 11, comprises horizontal nozzles de-

  terminating an extended and generally narrow rectangular air outlet port 89. A generally circular air inlet connection 90 is provided at the lower portion of the positive vent chamber 76 to establish communication with an inlet duct. suitable air 92, as illustrated in FIGS. 6a to 6c and 8a to 8c, which communicates with the air blower

72.

  The air outlet nozzle 89, of general horizontal orientation

  zontal, extends slightly above and parallel to the sur-

  upper face of the endless conveyor belt 12 which

  transports the aqueous mixture to the drying zone of the

  same to the arrow S. To be certain that the air exiting the outlet 89 is generally uniformly distributed within this orifice and reaches approximately perpendicularly to the plane of the outlet orifice 89 inclined baffles 94 and 96 divert the air so that it extends along the length of the positive ventilation chamber 76, while baffles 98, 100 and 102 ensure that the air leaving the nozzle 89 will be perpendicular to its exit plane and directed transversely to the upper surface of the endless conveyor belt 12 and in close parallelism

with her.

  The forced ventilation chamber 20 return air illus-

  in figs. 12 to 14 has a constitution that is quite similar

  ble to that of the positive outlet ventilation chamber 18

  air. Essentially, the total width of the ventilation chamber

  positive air return 20 is virtually identical to

  that of the positive ventilation chamber 18 air outlet.

  In addition, the air return chamber 20 is provided with side walls 104 extending into a horizontal wall 106 and a

  side wall 108 extending into a side wall 110 in-

  flicked upward to form a ventilating chamber

  112 and a convergent air inlet 114 whose upper surface 110 inclines down towards the positive ventilation chamber 112. As can be seen from the drawings, the wall 110 upward sloping protrudes beyond the bottom wall 106 to determine a 9. orifice much higher than the height of the air outlet nozzle 89 which corresponds to it and which is disposed opposite on the upper strand of the endless conveyor belt 12. The end walls 116 and 118 form a positive positive vent chamber and the air contained therein is withdrawn through a lower connection 120 for a conduit. A series

  baffles or dividing elements 122, 124 and 126 are

  within the return port 114.to direct air into the interior of the positive vent chamber 112 without

  undesirable turbulence or eddies.

  The return air coming out of the connection 120 passes through an elbow 128 to reach a duct 130 which leads to the fan 72 of a positive ventilation chamber 18 of food.

  located in the vicinity.

  The end walls 86, 118 and 88, 116, opposite and

  respective positive ventilation chambers 18 and 20 shown in FIG. 7 are connected by baffle plates 132 arranged transversely to the belt 12 and

  intended to reduce possible losses in the speed of

  air flow through the outlet ports 89 and flows toward the return ports 114 on the opposite side of the endless conveyor belt 12. The final air return positive ventilation chamber 20 located at downstream, shown in fig. 6c and 8c, may be provided with an outlet line 134 and a suitable engine-driven exhaust blower for ventilating the drying air loaded with moisture from

  10. If desired, this air can be dehumidifiable

  heated, and returned to the first positive outlet ventilation chamber 18 located upstream of the apparatus for

to be reused.

  The operation of the preferred embodiment of the apparatus

  The drying air filter of the invention is generally as follows: An aqueous slurry consisting of, for example, reconstituted tobacco, is disposed on the endless conveyor belt 12 which flows in the direction of arrow S upstream of

  the apparatus 10 to form a slurry coating whose thickness

  It is approximately 0.38 mm on the upper belt strand.

  The reconstituted tobacco slurry may contain 75 to 90%

  water-in-weight, or a composition as described in U.S. Patent Application No. 1,8,814 to Schmidt et al.

already mentioned.

  The tobacco porridge can be arranged on the belt

  endless conveyor 12 via an approved apparatus

  property (not shown) and known from the prior art, or at least

  yen of a device that makes it possible to make tobacco porridge

  and as described in US Patent Application 1,248 discloses

  January 5, 1979 in the name of Otto K. Schmidt, mentioned

here for reference.

  The air drying apparatus may consist of a

  of drying sections 16 connected in series along the

  course of the belt 12, as shown in FIG. 1. Each section

  air drying system 16 comprises a pair of ventilation chambers

  Positive air outlet and return air intake mounted to the op-

  placed one on the other on the opposite sides of the belt 12.

  According to a preferred arrangement of the air drying apparatus as schematically illustrated in FIG. 15, there are provided five drying sections 16 arranged in series to form an elongate slurry drying zone. As shown in the figure, the positive ventilation chambers 18 for air outlet and for return air return are alternately arranged on the

same side of the belt 12.

  When the upper run of the endless conveyor belt 12 which supports the slurry enters the first drying section 16 at the upstream or inlet end of the drying apparatus 10, the lower surface of the belt is exposed to

  a vapor atmosphere produced by a first gearbox

  can hang under the upper strand of the belt.

  The steam can be supplied to the steam box by a suitable source (not shown) at a pressure of 0.21 kg / cm 2 and

  a temperature of the vapor of between about 101 and 1020C.

  The cloud of steam that results below the belt 12 heats the latter, possibly at a temperature of 930C at the entrance of the device, thanks to the heat transfer that occurs, causes the evaporation of moisture content. in the

  boiling and the formation of a continuous film of vapor condenses

above the porridge.

  A drying air stream is projected onto the surface of the slurry transversely to the direction of travel of the

  belt 12 and from the first ventilating chamber

  positive air outlet 18 towards the air return ventilation chamber located directly opposite the first on the opposite side of the belt. Preferably, the air is dehumidified and preheated to a temperature of about

  1100C by an air pre-heater or a warm winding

  ghost (not shown). The drying air may be supplied to the apparatus at an initial volume of about 184 m 3 / min, with the air exiting the positive exhaust ventilation chamber 18 at a velocity between About 3,040 m / min, the speed

  preferred for a tobacco slurry being about 1.050 m / min.

  The upper slope of the inlet nozzle or the inlet of

  the positive air venting chamber 20 and the

  Baffle plates 132 extending across belt 12 and slurry to connect the ends of chamber 18 and chamber 20 to opposite sides of the belt ensure that

  drying air losses are kept to a minimum.

  Although the upper surface of the belt 12 may not be completely flat due to thermal distortions and operation, and although the slurry itself may have irregularities or obstructions on its surface, the drying air stream adheres closely to the surface due to the Coanda effect of the high velocity air stream

  travels. Essentially, the Coanda effect consists of a phenomenon

  leads to reunification of fluid jets, such as currents

  of air flowing at high speed, which smooth the surfaces

  mites, the flow of air curving around the obstructions and

tend to adhere to it.

  When the drying air crosses the width of the conveyor belt, the vapor film above the porridge

  is drawn by this current to the positive ventilation chamber.

  20 air return. Looks like. return can then be transferred

  re of the positive ventilation chamber 20 at the entrance of a

  positive outlet ventilation chamber 18 located immediately

  immediately upstream on the same side of the conveyor belt.

  12, and is then propagated across the surface of the slurry transverse to the belt in the opposite direction of the stream of air flowing in the preceding drying section 16. In fact, this determines an air sweep of the belt 12 and the slurry in opposite directions, which ensures a uniform drying sequence imposed on the slurry as

  it is transported in the air drying apparatus 10. As shown in the drawings, the return or recirculation of the air

  from positive ventilation chambers 20 back

  air to the air outlet chambers 18 creates a cycle of se-

  full air holster inside the unit. In addition, a separate steam box 14 is disposed below each drying section 16 to produce the necessary vaporization in

  the porridge in each section of the device.

* The apparatus 10 as illustrated here comprises five sec-

  air drying units, each preferably being one

  3.66 m so that the air dryer has

  a total length of 18.29 m. However, it is also possible

  within the scope of the invention to envisage a larger or smaller number of drying sections, depending on the type of material used in the slurry and the degree of drying that one

  research. In this respect, it is possible to change the length of

  operation of the basic apparatus without structural modification by incorporating bypass lines and valve devices between the individual drying sections of the air drying apparatus, thereby eliminating or adding

  operational drying sections.

  Various modifications can be made easily to the air drying apparatus, as will be appreciated by those skilled in the art

  on examining fig. 16 to 21 o the same components, or com-

  similar, are designated by the same numerical references

HAZARD.

  In the embodiment shown in FIG. 16, a

  series of air outlet lines 140 are arranged at inter-

  valleys across the conveyor belt 12 so as to

  project air currents along the whip course.

  In a position adjacent to the ducts 140 are disposed return air ducts 142 which allow the return of air

  which causes the vaporized moisture of the slurry.

  The embodiment of FIGS. 17 and 18 represents chambers

  150 air outlet positive ventilation ducts forming ducts

  drying air rents flowing from the sides of the conveyor belt 12 towards its longitudinal axis

  central perpendicular to the direction of the course of the cour-

  ROIE. The return air which contains moisture from the slurry passes into the return air duct 152 below which a baffle 154 guides air into the duct, 13. A suitable hood 256 disposed above the conduct of

  return air 152 sends the air into the surrounding atmosphere.

  The structure illustrated in FIG. 19 represents a device

  where the outlet air ducts 160 and 162 are placed transversely across the conveyor belt 12 and

  are intended to send drafts of drying air through

  to a slurry in a direction following the course of the conveyor belt and also against the current. Suitable hoods 164 may be disposed above the belt between lines 160 and 162 to diverge the air

  drying back loaded with moisture.

  As shown in figs. 20 and 21, the vertically disposed drying air outlet ducts 170 direct the air towards the bottom and radially outwardly over the slurry, and the return air which entrains moisture is directed to positive return ventilation chambers 172 that are arranged

  along both sides of the conveyor belt.

  It is understood that the various embodiments of

  the air-drying apparatus of the invention have been described at

  examples and that variations and refinements

  tail can be imagined without, for this, outside the scope of the invention.

14. 2463373

Claims (24)

R E V E N D I C A T IO N S   1. Apparatus for removing moisture from a constituent material   killed by an aqueous slurry, characterized in that it comprises, in combination (a) movable support means, generally horizontally, said slurry being supported on an upper surface thereof; (b) vapor ejection means disposed below said movable support means to provide a vapor atmosphere below the bottom surface of said movable support means to cause formation of a continuous film of condensed vapor from said slurry above said support means; -   (c) and means for directing a drying air stream on   long and above the upper surface of said means of sup-   mobile port and said slurry to remove steam   densing said slurry and dragging it with the drying air,   the result being that the slurry is dried at a speed   determined and makes it possible to obtain a dried substance uniform.   2. Apparatus according to claim 1, characterized in that said means for producing steam are constituted by   minus a steam boot comprising first and second chambers   spaced and parallel positive vapor venting bores disposed below the lower flanges of said   mobile support; a series of spaced steam pipes   extending between said first and second ventilating chambers   the said steam pipes communicating in   ternance with said first and second ventilating chambers   positive and a series of steam outlet orifices   in said conduit, said ports being directed upwardly toward the bottom surface of said slurry support means to determine said atmosphere of   vapor below said support means and transfer the heat   they come from the support means so that the boil-   lie forms said condensed vapor film.   3. Apparatus according to claim 2, characterized in that the support means of the slurry comprise a belt   endless conveyor with a flat upper strand,   lie being supported on this upper strand.   15. 4. Apparatus according to claim 3, characterized in that   the first and second positive ventilation chambers of va-   may extend respectively below the opposite flanges of the upper conveyor belt in the direction of travel of the belt, said steam outlet pipes   extending transversely to the belt.   5. Apparatus according to claim 3, characterized in that it comprises means for suspending the steam box in   below the upper end of the endless conveyor belt.   6. Apparatus according to claim 5, characterized in that the suspension means of the steam box comprises eye bolts attached to said steam box, these eye bolts being provided to be connected to cables or suspension chains. to hang the steam box on a structure overhanging support.   Apparatus according to claim 1, characterized in that   the mobile support means of the slurry comprise a   impermeable endless conveyor belt with a top strand   generally horizontal plane, said slurry being   carried on said upper strand of the belt.   8. Apparatus according to claim 7, characterized in that the endless conveyor belt is made of stainless steel. 9. Apparatus according to claim 1, characterized in that said means for passing the drying air stream   above the porridge include at least one chamber of   positive outlet air intake comprising an outlet nozzle   air extending along one side of said support means   bile of the porridge; and at least one positive return air ventilation chamber extending along the opposite side of said support means to the same length as the air outlet nozzle, said positive return air ventilation chamber comprising a air inlet duct for receiving   the flow of air from said outlet nozzle and the   condensed fear from the porridge and entrained therefrom between said positive output venting chambers and return of air.   10. Apparatus according to claim 9, characterized in that it comprises means for blowing into said positive air outlet ventilation chamber for sending pressurized drying air at high speed to said outlet nozzle. 'air. Apparatus according to claim 9, characterized in that   said exhaust air outlet nozzle comprises a   a narrow and elongated neck extending along and above said side of said movable carrier means of the slurry; and   least a baffle device located in said   to subdivide and orient the course followed by the air and which comes from it.   12. Apparatus according to claim 9, characterized in that it comprises a series of positive ventilation air outlet and return air chambers which are arranged on the sides   opposed said mobile support means of the slurry, the   said positive ventilation chambers being spaced along the path followed by said support means to define an extended drying zone for the slurry, said positive air outlet and return air ventilation chambers being   arranged alternately along said drying zone, each   - that a positive outlet ventilation chamber located on one side of said support means being associated with a positive return air ventilation chamber located on the opposite side on the   opposite side of said support means of the slurry.   13. Apparatus according to claim 12, characterized in that it comprises conduit means connecting at least some of said positive return air ventilation chambers to a   positive exhaust ventilation chamber adjacent to it and if-   killed at the upstream, arranged on the same side as the means of   carrying the slurry so as to determine a circuit of the drying air stream which is continuous within said zone   extended drying of the slurry.   14. Apparatus according to claim 12, characterized in that it comprises blowing means connected to each of said positive air outlet ventilation chambers for sending drying air at high speed to each of said nozzles of air outlet.   15. Apparatus according to claim 9, characterized in that said stream of air from the outlet nozzle of   said positive exhaust ventilation chamber is di-   rigged in close parallelism with the upper surface of said   support means for the slurry and essentially transverse   17. to the direction of the longitudinal movement of the said means of support.   Apparatus according to claim 1 characterized in that the air stream from said air outlet means is directed in close parallelism with the upper surface.   said means for supporting the slurry and generally in   rection of the movement of said support means of the slurry.   Apparatus according to claim 1, characterized in that the air stream from said air outlet means is directed in close parallelism with the upper surface.   said means for supporting the slurry and extending   edges of said slurry towards its center, generally transversely to the direction of movement of said support means of the slurry.   Apparatus according to claim 1, characterized in that said air stream from said air outlet means is directed in close parallelism with the upper surface   said means for supporting the slurry and extend in direction   radially along said surface.   Apparatus according to claim 12, characterized in that said steam ejection means comprises a boot   each opposing pair of ventilation chambers posi-   outlet and return air circuit comprising one of said   steam boxes associated with it.   20. Apparatus according to claim 1, characterized in that the vapor which comes from the steam ejection means out   at a pressure of about 0.21 kg / cm 2 and at a temperature of between about 102 and 104 ° C.   Apparatus according to claim 1, characterized in that   that the drying air passes through said slurry at a similar speed   taken between about 304 and 3.040 m / min.   22. Apparatus according to claim 21, characterized in that the drying air is at an initial temperature of approximately C. Apparatus according to claim 21, characterized in that   that the drying air is supplied at a volume of about 184 m 3 / min.   Apparatus according to claim 1, characterized in that   that the slurry consists of a reconstituted tobacco slurry   with a water content between approximately 75 and 90% in weight.